1. Field of the Invention
The present invention relates to a digital photo frame with a power saving function, and more particularly, to a digital photo frame that senses presence of a user within a specific range as a basis of power saving operations.
2. Description of the Prior Art
For an electronic device equipped with a display panel, such as a digital photo frame, a great amount of system power is consumed in operating the display panel. In portable products, which use batteries as a power source, standby time is greatly limited. Thus, power-saving design becomes a very important issue.
Taking a 3.5-inch digital photo frame as an example, typical power consumption of the display panel is roughly between 0.384 and 0.41 Watts, whereas power consumption of the rest of the digital photo frame amounts to only 0.85 Watts. In other words, the display panel consumes about one-third of the total system power. Thus, if power saving measures, such as turning off a backlight of the display panel, can be employed appropriately, e.g. when the display panel is not in use (for example: when the user leaves), the standby time of such portable products can be significantly increased.
Power saving mechanisms in current portable computers and personal computers are mostly based on trigger signals from a keyboard or a mouse, whereas flatscreen TVs typically utilize light sensors to sense surrounding light, and adjust light intensity of their screen accordingly. However, in each of these two methods, the electronic device cannot accurately detect the presence of users when performing the power saving operations. This means the display panels remain in full operation when the user leaves. For example, a digital photo frame may continue displaying pictures on its display panel when the user leaves, which causes unnecessary waste of system power. Therefore, if appropriate sensors can be incorporated for detecting the presence of the user, the power saving operations, such as turning off the backlight of the display panel, can be performed more accurately, such that the standby time of the portable product can be increased significantly.